Honda HRX 426 Lawn Mower Speed

Discussion in 'In the Garden' started by Hysteresis, 18 Oct 2013.

  1. Hysteresis

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    I have a Honda HRX 426 lawn Mower and its speed is best described as a crawl. I have talked to the local Honda Service agent and Indeed Honda themselves to try to get advice on how to speed the thing up. Honda just do not want to know as they say the speed is as designed, and the local agent just looks blank at em when I ask the question.
    I have found that I can increase the speed using an elastic band to hold back one of the feedback arms for the Governor. I have tried to locate the supplier of a coiled spring to replace the rubber band without success.
    So my question is, does anyone have any ideas as to how I can speed up this dreadfully slow mower?. I think the engine is a Briggs and Stratton and I can find no adjustment screws which will increase the engine speed set point.
     
  2. Burnerman

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    A Briggs engine on a Honda mower? Surely not :eek: :p
    Difficult to explain, but examine the governor linkage to the carburettor. You'll find that this is spring controlled and you can usually get the speed up not by messing with the spring, but rather by carefull bending of the metalwork that the spring connects to.
    Sorry to be a bit vague - its easier with the machine present!
    I assume that full throttle is being achieved at the handle end - and any more throttle puts the choke on.
    John :)
     
  3. Hysteresis

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    Sorry John, I think you are right, it must be a Honda engine. Also you are correct in that the speed setting is full from the Handle and ant further movement applies the choke.
    I can locate a mechanism from the Governor to the Carburettor and it is weird as the link has a spring coiled around it. Just what this feedback arm spring is achieving is a mystery as the link and the spring are attached to the governor arm at the same point and from what I can see, they are attached to the Carburettor almost at the same point. If I pull the governor arm back the engine speeds up. so it would appear that this linkage (governor to Carb) needs to be longer not shorter. Does that seem to be right.
    The governor lever has a spring attached at the other end of it which is linked to the speed control mechanism. I noticed that this spring can be attached to one of two holes in the governor arm. so I repositioned this spring to the alternative connecting hole but it made little difference to the speed of the engine. The only success I have is that if I attach a rubber band to the governor feedback arm and pull this arm backwards away from the Carburettor. Does any of this make any sense to you. It certainly doesn't to me. I am trying to locate a spring which would replace the rubber band to achieve a reasonable speed on this machine.
     
  4. Burnerman

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    Those long springs over the linkage rod serve a damping effect, but only when the holes in the quadrants start to wear.
    I'm going to be really boring here and ask you to post some pics if you can of the linkages to the carb and from the governor.
    Believe it or not, I have done this job before and it involved squeezing a part of the linkage with pliers - but not the round links or springs, more like two lugs somewhere near the bottom.
    Certainly it was worth doing - apart from the machine going faster, the draught from the blade pressurised the grass box which improved grass collection no end.
    John :)
     
  5. Hysteresis

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    I have difficulty posting Pictures on DIYnot, but I will try again tomorrow, it will need a removal of the inlet air filter to get a view of the linkage.
    Thanks so much for your help.
     
  6. Hysteresis

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    Hi John/burnerman.
    Here is the image of the linkage from the Governor to the Carb.
    There is another connection from the bottom governor lever to the throttle control the spring of which can be seen at about 8'o'clock position near the Fuel cut off valve.. This linkage also effects the speed set point and there are two holes at the gov linkage available to attach the spring. I have tried both holes and it does not appear to make any difference.
    Hope this image appears in the posting.
     
  7. Burnerman

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    Ok, good photo, thanks!
    On this machine, the high speed adjustment is actually by the screw that's enclosed inside that black plastic tube.....the screw is tamper proof Torx, and needs to be unscrewed to make the machine rev more. Can you give that a try?
    John :)
     
  8. Hysteresis

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    I have tried that. What happens is that when the full speed setting is reached any further adjustment of that screw starts to apply the choke, hence my investigation towards the adjusting the governor setting.
    The solution I have been using so far is to attach a rubber band to the goveror lever at the right hand end of the Carb/governor linkage, I then attach the other end of the rubber band too an anchor point. This has the effect of increasing the governor set point and hence a faster mower speed. The disadvantage of this solution is the UV degradation of the rubber band. Only a small disadvantage to replace the rubber band. I thought there must be a way of resetting the governor set point.
     
  9. Burnerman

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    Hmmm right, I see what you are trying to achieve with a rubber band, and that's fair enough!
    The only thing I can do now is to look at a similar machine at home - but that won't be until Monday. I have a feeling that juggling with that torx screw and the throttle cable will achieve what you need.
    The governor on these is an internal bob weight type, and if the clearance between that and the rod that comes out of the engine is too great then low revving could be the result - but I can't say for sure!
    John :)
     
  10. Hysteresis

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    Thanks for your Help and interest John.
    My input for what it is worth (which is very little), the Torq Screw and speed cable are of course connected but in the end the rotation of the shaft which goes into the throttle is the objective. This is presently at it maximum position, just before the lever reaches the choke activation lever, so any further adjustment to speed up the machine will inevitably apply the choke, hence my arrival at the conclusion that the root of the speed problem is governor related.
    The result of discussing this with Honda and a local service guy was that Honda set the speed of this machine slow so that the roller get the opportunity to give a striped lawn, a bit of poetic licence in my view, but they said that speeding up the machine is not recommended as this will affect the life of the engine. Don't really accept that to be honest. The fact is that the damn machine is just too slow. Maybe the solution will be to replace my rubber band with a spring if I can locate one with similar characteristics.
     
  11. Burnerman

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    Just to resurrect this one - may be a bit late though!
    See the spring at the bottom, behind the fuel tap?
    Bend the bracket at the left hand end with pliers so the spring no longer has slack, and try that.
    John :)
     
  12. Hysteresis

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    Thanks for the suggestion John, I will try that tomorrow and let you know how I get on. I did try adjusting that particular spring last weekend, there are two holes in the governor bracket at the left hand end of that spring and I repositioned the spring into the hole which would take up any slack, although I did not check if there was still a little slack on it. My adjustment didn't speed up the machine, but tomorrow I will investigate further.
    Thanks again for your help.
     
  13. Hysteresis

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    Hi John,
    I have just inspected the spring to which you referred. As I said in my last posting, I had a go at that spring a couple of weeks ago at which Time I reconnected the Right Hand end of the spring to a second hole in the bracket on the governor. (in my mail I wrongly stated that I had done this at the Left Hand end of the Spring) This reconnection eliminated any slack on that spring and the spring is now under permanent tension so there is no slack. There is very little scope for bending the bracket at the left hand end of the spring connection which is of course the connection to the Carburettor.
    I have pushed the right hand end bracket i.e. the one connected to the governor with a screwdriver in the direction of the Carburettor (this rotates the Governor shaft clockwise)and the speed of the machine increases as expected. In fact this operation is identical to the effect I get with the elastic band solution to which I previously referred, this elastic band in effect rotates the governor shaft clockwise and achieves the desired effect.
    What is puzzling me here is that without any adjustment engineered into the design by Honda, the governor speed setting is determined my fixed linkages and as such no tolerance allowed for manufacturing variations . My experience, which I might add is very limited, of all engine manufacturing is that final setting are achieved with fine tuning screw adjustments, hence my original posting asking if anyone could identify such screw adjustments. Means of adjusting the governor set point is available with my silly elastic band solution, but it appears Honda have not engineered an adjustment into their design therefore the final speed setting is what ever the initial assembly determines.
    What do you think of a solution where by the top linkage from the Governor to the Carburettor (the one with the spring which does nothing wrapped around it) is modified so that it can be lengthened and as such increase the governor set point. I am not sure this would work as it would be a fixed extension to the linkage whereas the rubber band solution is a spring adjustment.
    I am sure we can determine an acceptable solution to this poor Honda design with our joint application to the problem. The only addition to the design I have at the moment is replacing the Rubber Band with a steel spring, but I am sure there must be a better solution, hence my suggestion of making the length of upper Governor/Carb linkage adjustable so that it could be made longer, But will it work?
    Thanks again for your interest ind help.
    Ian
     
  14. Mursal

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    Just a thought but, did you try tightening the spring under the oil filler, or shorten the rod going from the top of the carb to the governor, by bending it slightly? Actually shortening the working length of the rod
     
  15. Hysteresis

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    I Can't identify the spring you mean. Do you mean the spring connecting the bottom lever on the governor to the throttle control on the carb. If so I have tried this and is makes little difference. With respect to the rod from the Governor to the Carb, I have played around with that but the only success I seem to have is pulling the governor lever with a rubber band towards the back of the machine, which is rather like lengthening this rod !!!
    However if I shortened the rod maybe this will have the effect of opening the throttle for a given governor setting so maybe that would work. I resist bending this rod as it is rather a permanent adjustment and maybe not recoverable from, but I may be forced into giving it a go. I will let you know.
    Thanks for your help.
     

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